Method for splicing a laid rope

ABSTRACT

Method to make a splice in a laid rope construction containing at least two strands includes splitting one end of the laid rope into a first part having a first number of strands and a second part having a second number of strands, then tucking the first part of the first rope from a first direction into an opening in the laid rope, and thereafter tucking the second part into the opening from an opposite direction. The first and second parts are tucked at least 3 times into additional openings being separated from one another such that the first part and the second part cross over at least once all the strands of the laid rope and leave the second rope at the last opening.

This application is the U.S. national phase of international applicationPCT/NL2003/000756 filed 31 Oct. 2003 which designated the U.S. andclaims benefit of EP 02079571.2, dated 1 Nov. 2002, the entire contentof which is hereby incorporated by reference.

FIELD OF INVENTION

The invention relates to a method to make a splice in a laid ropeconstruction containing at least two strands and to a new spliced ropeconstruction obtainable by said method.

BACKGROUND AND SUMMARY OF THE INVENTION

Splices are used amongst others in eye splices and end-for-end splicesfor e.g. ropes, grommets, hawsers and round slings. Splices are alsoused in the production of endless ropes.

A method to make a splice in a laid rope is known from “The SplicingHandbook of Barbara Merry”, ISBN 0-07-135438-7. Herein a splice is madeby splitting a rope in its single strands and tucking these singlestrands in another part of the rope in case of an eye splice, or inanother rope in cases where two ropes are to be connected with eachother. In the known method typically all constituting strands areseparately tucked in another rope or in another part of the same rope tomake an eye.

A connection made with a known splice in a rope has a lower strengththan the strength of the original rope. This means that the strengthretention, hereinafter referred to as “efficiency”, of the knownsplices, being the relative strength of the splice and the strength ofthe original rope, is below 100%.

The invention aims to provide a method for making a splice in a laidrope construction with at least two-strand ropes, which method resultsin a splice with a higher efficiency than the known splice.

This aim is achieved with a method comprising the steps of:

-   a) Splitting one end of a first rope end in a first and a second    part comprising respectively a first and a second number of strands,    the first number of strands being at most one more than the second    number of strands;-   b) Tucking the first part from one side into an opening in a second    rope, such that the opening has a first number of strands of the    second rope on one side and a second number of strands on the other    side, the first and second number differing at most by one;-   c) Tucking the second part from the other side into the opening in    the second rope;-   d) Repeating steps b) and c) at least 3, respectively at least 3+1    times, whereby the respective openings in the second rope are    separated such that the first and the second part have crossed over    at least all the strands of the second rope once and the first and    second part leave the second rope at respective last openings.

With the method according to the invention it was surprisingly foundthat the efficiency is higher than the efficiency of the known splice.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1–4 schematically depict a sequence of splicing a laid rope inaccordance with the present invention.

The invention provides a method to make a splice in a laid ropeconstruction with at least two strands. Ropes containing only twostrands are not commonly used per se, but may form part of a larger ropeconstruction wherein they can be connected with a splice. Preferably,the laid rope contains at least three strands, since such ropesgenerally are more symmetrical. In a preferred embodiment, the ropecontains 3, 4 or 6 strands.

DETAILED DESCRIPTION OF THE INVENTION

In the method of the invention, as depicted schematically by FIGS. 1–4one end (100) of a first rope (200) is split in a first part (101) and asecond part (102) comprising respectively a first and second number ofstrands, the first part (101) having a number of strands being at mostone more than the number of strands in the second part (102). This meansthat a 3-strand rope is split in a first part (101) with 2 strands and asecond part (102) with only 1 strand. A 4-strand rope is split in twoparts of 2 strands and a 6-strand rope in two parts of 3 strands.

In the method of the invention the first part (101) is tucked from oneside into an opening (400) in another part of the rope (200) or a secondrope (not shown), such that the opening (400) has a first number ofstrands of the rope (200) on one side and a second number of strands onthe other side, wherein the first and second number differ at most byone. (See FIG. 1). In lieu of using another part of the rope (200) asdepicted in FIGS. 1–4, the methods of the present invention may beemployed using a second or other rope as such, in case two ropes are tobe connected with each other. Thus, as depicted in FIGS. 1–4, usinganother part of the rope (200) the splice will cause an eye to be made.A second rope may also be the other end of the first rope in case around sling or a grommet is to be made. Generally the first and thesecond rope have the same number of strands.

In case the first and second rope have 3 strands each, the said openinghas 2 strands on one side and 1 strand on the other side. If the firstand second rope has 4 or 6 strands, the said opening has 2, respectively3 strands on both sides.

In the method of the invention as shown in FIG. 2, the second part (102)is tucked from the other side in the same opening (400) in the rope(200), which implies that both parts (101,102) of the rope (200) aretucked in different directions through the opening (400) in the rope(200).

In the method of the invention as shown in FIGS. 3 and 4, steps b) andc) are repeated at least 3 times, whereby the respective openings (400)and (500) are separated such that the first part (101) and the secondpart (102) have crossed over at least all the strands of the rope (200)once and the first and second parts (101), (102), respectively, leavethe rope (200) at respective last openings. The sequence wherein step b)and c) are repeated is of no importance for the efficiency of theresulting splice. It may be advantageous to first tuck the first part(101) several times, and than the second part (102), because this willsave time.

Preferably, both parts are tensioned after every step b) and c), beforecontinuing with the next steps, to result in a better and more compactsplice construction.

After at least 3 tucks for the first, and at least 3+1 tucks for thesecond part, the splice can be tapered. With at least 3+1 it is meantthat the second part has at least one more tuck than the first part inorder to avoid the tapering of the two parts to commence at the sameplace.

The tapering can be done by cutting off half or one third of the firstand second part of the first rope, and continue the steps b) and c) foranother three or four times. This process of tapering can be repeateduntil the remaining first and second part are being cut off completely.

Preferably the splice is tapered by:

-   e) cutting off a complete strand from the first and the second part    where they leave the last opening,-   f) repeating step b) and c) for at least 3 times-   g) repeating steps e) and f) until the last strand rope is being cut    off.

The advantage of the method according to the invention including thetapering steps is that it is easier to determine one half or one thirdin a part consisting of two respectively three strand ropes than to findhalf of or one third of the yarns in one strand rope, especially if asplice is to be made in multi-strand rope construction.

The sequence of steps as described above for the process according tothe invention is especially suited for making an eye in a rope, whereinoptionally a thimble can be used around which the eye is made. If tworopes, either two ends from the same rope or from two different ropesare to be connected, the same sequence of steps is preferably repeatedfor the end or tail of the second rope, which end is tucked into thefirst rope, in order to make an optimal connection.

The rope used in the method of the invention can be made from anymaterial commonly used for yarns, being of natural or synthetic origin.Examples of synthetic materials used in ropes with at least two strandsare polyester, nylon, polypropylene, aramids, polyethylene, and highmolecular weight polyethylene.

An additional advantage of the method according to the invention is,that with this method a splice is made much faster than with the knownmethod. This advantage is particularly relevant for multi-strand ropes,and especially for ropes produced from highly drawn fibers of highmolecular weight linear polyethylene. Because of the low coefficient offriction of fibres and ropes made from this material, a splice of arelatively high number of tucks is generally required to obtain a goodefficiency, e.g. a splice of at least 9 tucks. By using coated highmolecular weight polyethylene ropes, the number of tucks required toobtain a good efficiency can be brought down to about 7. This highnumber of tucks combined with advantage of the faster production of thesplice according to the invention with respect to the known splice,makes that the method of the invention is preferably used in a ropecomprising highly drawn fibres of high-molecular weight linearpolyethylene. High molecular weight here means a weight averagemolecular weight (or molar mass) of at least 400,000 g/mol.

Linear polyethylene here means polyethylene having less than 1 sidechain or branch per 100 C atoms, preferably less than 1 side chain per300 C atoms, a side chain containing at least 10 C atoms. Thepolyethylene may also contain up to 5 mol % of one or more other alkenesthat are copolymerisable therewith, such as propylene, butene, pentene,4-methylpentene, or octene.

Preferably, use is made of polyethylene fibres consisting ofpolyethylene filaments prepared by a gel spinning process as describedin for example GB-A-2042414, GB-A-2051667, or WO01/73173. This processessentially comprises the preparation of a solution of a polyolefin ofhigh intrinsic viscosity, spinning the solution into filaments at atemperature above the dissolving temperature, cooling down the filamentsto below the gelling temperature of the solution so that gelling occurs,and drawing the filaments before, during or after removal of thesolvent.

The invention further relates to a spliced rope construction obtainableby the method of the invention, to the use of this splicing method tomake an eye in a rope, as well as for end-for-end splices in ropes,grommets, hawsers, round slings, or endless ropes.

The invention further relates to a spliced rope construction accordingto the inventions being for example a grommet, a hawser, a round slingor an endless rope.

The invention is further elucidated by the following ExamplesComparative Experiments, which are carried out with a 3-strand laid ropemade of highly-drawn fibres of high-molecular weight linear polyethylene(Dyneema® SK75, ex DSM High Performance Fibers, NL), having aconstruction of 3×24×1/1760 dTex, 39 g/m and a lay length of 62 mm.

The ropes were coated with a Lago L45 (ex GOVI, Belgium)/water mixture(1 part by weight Lago and 2 parts by weight of water) such that afterdrying the rope comprises 16 mass % (relative to the weight of the rope)of the coating material.

The ropes with a length between bollards of 210 cm were subjected to apre-stress of 4000N and a tensile test was carried out on a 100 tonsZwick tensile tester with a speed of 150 mm/min.

EXAMPLE I

An end-for-end splice was made in two ropes of the above mentionedconstruction with 6 tucks, tapered in 2 steps of each 3 tucks(hereinafter referred to as a 6/3/3 splice). The time to make the spliceaccording to the invention turned out to be 2×5 minutes. The tensilestrength was 76.4 kN, which is an efficiency of 100%.

EXAMPLE II

A single roundsling was made with the rope of the above-mentionedconstruction and a (8/3/3) splice according to the invention. Thetensile strength was 2×74.8 kN, which corresponds to an efficiency of98%

EXAMPLE III

A rope of the above-mentioned construction with two eye-splices (6/3/3)and one end-for-end splice in the middle (8/3/3) was made with splicesaccording to the invention. The tensile strength of this constructionturned out to be 74.5 kN, which corresponds with an efficiency of 97%

Comparative Experiment A

An end-for end splice was made in two ropes of the above-mentionedconstruction with 6 tucks, tapered in 2 steps of 3 tucks, but using asplicing method according to the state of the art, as described in “TheSplicing Handbook of Barbara Merry” (ISBN 0-07-135438-7). The time tomake this splice turned out to be 2×20 minutes. The tensile strength was71.3 kN, which is a an efficiency of 93%.

Comparative Experiment B

Example II was repeated with a splice with 8 tucks, tapered in 2 stepsof 3 tucks, according to the state of the art mentioned in ComparativeExample A. The strength of this splice was 71.4 kN, which correspondswith an efficiency of 93%.

1. Method to make a splice in a laid rope construction containing atleast two strands comprising the steps of: a) splitting one end of afirst rope into a first part having a first number of strands and asecond part having a second number of strands, the first number ofstrands being at most one more than the second number of strands; b)tucking the first part of the first rope from a first direction into afirst opening in a second rope which splits the second rope into firstand second groupings of strands having respective numbers of strandsdiffering by at most one strand, wherein the first grouping of strandsis positioned on one side of the first part of the first rope and thesecond grouping of strands is positioned on another side of the firstpart of the first rope which is opposite to said one side; c) tuckingthe second part of the first rope into the first opening in the secondrope from a second direction which is opposite to the first directionfrom which the first part of the first rope is tucked into the firstopening according to step b); d) repeating steps b) and c) at least 3times, the openings in the second rope being separated from one anothersuch that the first and the second parts of the first rope cross over atleast once all the strands of the second rope, wherein each of the firstand second parts of the first rope leave the second rope at a lastopening.
 2. Method according to claim 1, wherein the laid ropeconstruction contains at least three strands.
 3. Method according toclaim 1, further comprising the steps of: e) cutting a complete strandfrom the first and the second part where they leave the last opening;repeating steps b) and c) at least 3 times; g) repeating steps e) and f)until the last strand is cut off.
 4. Spliced rope constructionobtainable by the method of claim
 1. 5. Spliced rope construction ofclaim 4, containing an eye splice, and/or an end- for-end splice. 6.Spliced rope construction of claim 4, being a grommet, a hawser, a roundsling or an endless rope.
 7. Spliced rope construction, wherein in stepd) of claim 1, steps b) and c) are repeated at least 3 and at least 3+1times, respectively.